您可以将Column的crossAxisAlignment添加到strech

crossAxisAlignment: CrossAxisAlignment.stretch

SizedBox.expand会导致DataTable的高度无限，而SingleChildScrollView不喜欢这样，因为您只想跨越父对象的宽度，所以可以使用LayoutBuilder来获得您所关心的父对象的大小，然后将DataTable Package 在ConstrainedBox中。

Widget build(BuildContext context) {
  return Scaffold(
    body: LayoutBuilder(
      builder: (context, constraints) => SingleChildScrollView(
        child: Column(
          children: [
            const Text('My Text'),
            Container(
              alignment: Alignment.topLeft,
              child: SingleChildScrollView(
                scrollDirection: Axis.horizontal,
                child: ConstrainedBox(
                  constraints: BoxConstraints(minWidth: constraints.minWidth),
                  child: DataTable(columns: [], rows: []),
                ),
              ),
            ),
          ],
        ),
      ),
    ),
  );
}

这是一个问题，不完整性，在一个漂亮的小部件，即数据表中，我在生产代码中遇到了这个问题，这个解决方案在一半以上的实验室设备上工作：

ConstrainedBox(
        constraints: BoxConstraints.expand( 
                  width: MediaQuery.of(context).size.width
        ),
child: DataTable( // columns and rows.),)

但是您知道什么在%100台设备上令人惊讶地起作用吗？这就是：

Row( // a dirty trick to make the DataTable fit width
      children: <Widget>[ 
        Expanded(
          child: SingleChildScrollView(
          scrollDirection: Axis.vertical,
          child: DataTable(...) ...]//row children

注意：行只有一个子级Expanded，它包含一个SingleChildScrollView，SingleChildScrollView包含DataTable。
注意，这样您就可以t use SingleChileScrollView with scrollDirection: Axis.horizontal, in case you need it, but you don t，否则这个问题将与您的用例无关。
如果Flutter团队的某个人读到这篇文章，请丰富DataTable小部件，它将使flutter具有竞争力和强大，如果做得好，flutter可能会掩盖android自己的原生API。

对于DataTable小部件，此代码适用于将dataTable宽度视为与设备宽度匹配的父项，

代码片段：

ConstrainedBox(
constraints: 
BoxConstraints.expand(
   width: MediaQuery.of(context).size.width
),
child: 
DataTable(
    // inside dataTable widget you must have columns and rows.),)

您可以使用以下属性删除列之间的空格

columnSpacing: 0,

注：

使用ConstrainedBox小工具解决了您的问题，

constraints: BoxConstraints.expand(width: MediaQuery.of(context).size.width),

完整代码：
注意：在此示例代码中，我介绍了排序和编辑DataTable小部件的概念。

• 库文件夹中必须有此类 *

1. main.dart
2. DataTableDemo.dart
3. customer.dart

main.dart类代码

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'DataTableDemo.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: DataTableDemo(),
    );
  }
}

数据表演示.dart类代码

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'customer.dart';

class DataTableDemo extends StatefulWidget {
  DataTableDemo() : super();
  final String title = "Data Table";

  @override
  DataTableDemoState createState() => DataTableDemoState();
}

class DataTableDemoState extends State<DataTableDemo> {
  List<customer> users;
  List<customer> selectedUsers;
  bool sort;
  TextEditingController _controller;
  int iSortColumnIndex = 0;
  int iContact;

  @override
  void initState() {
    sort = false;
    selectedUsers = [];
    users = customer.getUsers();

    _controller = new TextEditingController();

    super.initState();
  }

  onSortColum(int columnIndex, bool ascending) {
    if (columnIndex == 0) {
      if (ascending) {
        users.sort((a, b) => a.firstName.compareTo(b.firstName));
      } else {
        users.sort((a, b) => b.firstName.compareTo(a.firstName));
      }
    }
  }

  onSelectedRow(bool selected, customer user) async {
    setState(() {
      if (selected) {
        selectedUsers.add(user);
      } else {
        selectedUsers.remove(user);
      }
    });
  }

  deleteSelected() async {
    setState(() {
      if (selectedUsers.isNotEmpty) {
        List<customer> temp = [];
        temp.addAll(selectedUsers);
        for (customer user in temp) {
          users.remove(user);
          selectedUsers.remove(user);
        }
      }
    });
  }

  SingleChildScrollView dataBody() {
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: ConstrainedBox(
        constraints: BoxConstraints.expand(width: MediaQuery.of(context).size.width),
        child: DataTable(
          sortAscending: sort,
          sortColumnIndex: iSortColumnIndex,
          columns: [
            DataColumn(
                label: Text("FIRST NAME"),
                numeric: false,
                tooltip: "This is First Name",
                onSort: (columnIndex, ascending) {
                  setState(() {
                    sort = !sort;
                  });
                  onSortColum(columnIndex, ascending);
                }),
            DataColumn(
              label: Text("LAST NAME"),
              numeric: false,
              tooltip: "This is Last Name",
            ),
            DataColumn(label: Text("CONTACT NO"), numeric: false, tooltip: "This is Contact No")
          ],
          columnSpacing: 2,
          rows: users
              .map(
                (user) => DataRow(
                    selected: selectedUsers.contains(user),
                    onSelectChanged: (b) {
                      print("Onselect");
                      onSelectedRow(b, user);
                    },
                    cells: [
                      DataCell(
                        Text(user.firstName),
                        onTap: () {
                          print('Selected ${user.firstName}');
                        },
                      ),
                      DataCell(
                        Text(user.lastName),
                      ),
                      DataCell(Text("${user.iContactNo}"),
                          showEditIcon: true, onTap: () => showEditDialog(user))
                    ]),
              )
              .toList(),
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: SafeArea(
        child: Column(
          mainAxisSize: MainAxisSize.max,
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.stretch,
//          verticalDirection: VerticalDirection.down,
          children: <Widget>[
            Expanded(
              child: Container(
                child: dataBody(),
              ),
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                Padding(
                  padding: EdgeInsets.all(20.0),
                  child: OutlineButton(
                    child: Text('SELECTED ${selectedUsers.length}'),
                    onPressed: () {},
                  ),
                ),
                Padding(
                  padding: EdgeInsets.all(20.0),
                  child: OutlineButton(
                    child: Text('DELETE SELECTED'),
                    onPressed: selectedUsers.isEmpty ? null : () => deleteSelected(),
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  void showEditDialog(customer user) {
    String sPreviousText = user.iContactNo.toString();
    String sCurrentText;
    _controller.text = sPreviousText;

    showDialog(
      barrierDismissible: false,
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: new Text("Edit Contact No"),
          content: new TextFormField(
            controller: _controller,
            keyboardType: TextInputType.number,
            decoration: InputDecoration(labelText: 'Enter an Contact No'),
            onChanged: (input) {
              if (input.length > 0) {
                sCurrentText = input;
                iContact = int.parse(input);
              }
            },
          ),
          actions: <Widget>[
            new FlatButton(
              child: new Text("Save"),
              onPressed: () {
                setState(() {
                  if (sCurrentText != null && sCurrentText.length > 0) user.iContactNo = iContact;
                });
                Navigator.of(context).pop();
              },
            ),
            new FlatButton(
              child: new Text("Cancel"),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }
}

客户.dart类代码

class customer {
  String firstName;
  String lastName;
  int iContactNo;

  customer({this.firstName, this.lastName,this.iContactNo});

  static List<customer> getUsers() {
    return <customer>[
      customer(firstName: "Aaryan", lastName: "Shah",iContactNo: 123456897),
      customer(firstName: "Ben", lastName: "John",iContactNo: 78879546),
      customer(firstName: "Carrie", lastName: "Brown",iContactNo: 7895687),
      customer(firstName: "Deep", lastName: "Sen",iContactNo: 123564),
      customer(firstName: "Emily", lastName: "Jane", iContactNo: 5454698756),
    ];
  }
}

在Container中设置datatable，并将容器的width设置为double.infinity

Container(
    width: double.infinity,
    child: DataTable(
      columns: _columns,
      rows: _rows,
    ));

简单回答：

用Container()和width: double.infinity() Package 数据表。

Container(
            width: double.infinity,
            child: DataTable( 
    
            ..
            .

我的首选方式

您可以在www.example.com上使用DataTable 2包pub.dev
https://pub.dev/packages/data_table_2
这个软件包给予了DataTable2()小工具，默认情况下会扩展到可用空间。你还可以得到更多的选项，如ColumnSize等。

只需用Sizedbox Package DataTable并将宽度赋给double.infinity。

SizedBox(
  width: double.infinity,
  child: DataTable()
)

只需用定义了固定 width 的容器 Package 数据表，一切都应该正常。

甚至当你需要在一个屏幕上有多个表的时候，这对我来说也很有效。

final screenWidth = MediaQuery.of(context).size.width;
Scaffold(
  body: SingleChildScrollView(child:Container(
    child: Column(
      children: [
        Container(
            width: screenWidth, // <- important for full screen width
            padding: EdgeInsets.fromLTRB(0, 2, 0, 2),
            child: buildFirstTable() // returns a datatable
        ),
        Container(
            width: screenWidth, // <- this is important
            padding: EdgeInsets.fromLTRB(0, 2, 0, 2),
            child: buildSecondTable() // returns a datatable
        )
    ])
  ))
)

这也适用于单表只是 Package 与容器与所需的宽度。

SingleChildScrollView(
        child: Card(
          child: SizedBox(
            width: double.infinity,
            child: DataTable(columns:_columns, rows:_rows),
          ),
        ),
      ),